Integrated circuit chips have now been fabricated for a few decades. During such period of time, the technology of fabricating the integrated circuit chips has been progressively advanced. For example, only a few years ago, the thickness of the electrical leads between different components on an integrated circuit chip was in the order of a few microns. Now the thickness of leads between different components in an integrated circuit chip is in the order of a small fraction of a micron. A few years ago, the rate of rejection of integrated circuit chips as a result of imperfect fabrication of the chips was relatively high in comparison to the present rate of rejection of integrated circuit chips. All of the above advances have resulted from significant improvements in the equipment for fabricating the chips and for checking the parameters of the chips after each successive layer has been deposited on the chips.
In spite of the considerable advances made over the years in equipment for, and methods of, fabricating integrated circuit chips and in the construction and operation of the integrated circuit chips, problems still remain. These problems have become aggravated as the micron thickness of the electrical leads between components has progressively decreased in size. Furthermore, the range of parameters for operating the integrated circuit chips has progressively increased, partially as a result of the use of the integrated circuit chips in applications not previously contemplated. For example, the range of operating temperatures and power levels in different applications has progressively increased so that uses resulting in microscopically localized temperatures as high as 600.degree. C. are often required.
There are other instances where problems exist in integrated circuit chips even with the advances which have been made over the years. Grooves are often provided in integrated circuit chips for different purposes. For example, grooves are often provided to receive vias for interconnections between electrical components in different layers on the integrated circuit chip. The grooves are defined by walls which are coated with layers, called barrier layers, to provide material isolation. The grooves may then be filled with an electrically conductive material which constitutes the via. As the micron size of the leads on integrated circuit chips has decreased in size, the grooves have decreased in size.
It has been difficult to coat the walls of the grooves with barrier layers of a substantially uniform thickness. It has also been difficult to coat the walls of the grooves with barrier layer material so that conductive material from a conductive layer on the external surface of the groove wall will not leak through barrier layers disposed between the conductive layer and the substrate and affect the electrical properties of the substrate.
The difficulties of providing a satisfactory deposition of barrier layer material on the walls of a groove have been compounded because the range of operating parameters has increased through the years. For example, the range of microscopically localized operating temperatures of the integrated circuit chip has increased to approximately 600.degree. C. and even higher. At such high temperatures, the barrier layers between the exposed conductive layers and the substrate provide diffusion paths for the material in the conductive layer to leak to the substrate along stress-relieving microcracks in the barrier layer. This conductive material has then combined with the substrate material and the combination has significantly lowered the electrical performance of the substrate so that the operation of the electrical circuitry on the substrate is significantly impaired.